Normalizing Anti-Thrombin III for heparin management during routine cardiopulmonary bypass for congenital cardiothoracic surgery: A single institution practice review

INTRODUCTION

Over the past decade, there has been an increase in the use of recombinant Anti-Thrombin III (AT-III) administration during neonatal and pediatric short- and long-term mechanical support for the replacement of acquired deficiencies. Recombinant AT-III (Thrombate) administration is an FDA licensed drug indicated primarily for patients with hereditary deficiency to treat and prevent thromboembolism and secondarily to prevent peri-operative and peri-partum thromboembolism. Herein we propose further use of Thrombate for primary AT-III deficiency of the newborn as well as for acquired dilution and consumption secondary to cardiopulmonary bypass (CPB).

METHODOLOGY

All patients undergoing CPB obtain a preoperative AT-III level. Patients with identified deficiencies are normalized in the OR using recombinant AT-III as a patient load, in the CPB prime, or both. Patient baseline Heparin Dose Response (HDR) is assessed using the Heparin Management System (HMS) before being exposed to AT-III. If a patient load of AT-III is given, a second HDR is obtained and this AT-III Corrected HDR is used as the primary goal during CPB. Once CPB is initiated, an AT-III level is obtained with the first patient blood analysis. A subtherapeutic level results in an additional dose of AT-III. During the rewarm period, a final AT-III level is obtained and AT-III treated once again if subtherapeutic. A retrospective, matched analysis review of practice analyzing two groups, a Study Group (Repeat HDR, May 2022 onward) and Matched Group (Without Repeat HDR, July 2019 to April 2022), for age (D), weight (Kg) and operation was conducted. The focus of the study was to determine any change in heparin sensitivity identified post AT-III patient bolus load in the HDR (U/mL), Slope (U/mL/s), ACT (s), and total amount of heparin on CPB (U) and protamine (mg) used in each group.

RESULTS

No significance was seen in Baseline AT-III (%), post heparin load HDR (U/mL), first CPB ACT (s), first CPB HDR (U/mL), or total CPB heparin (u/Kg) between the two groups. Statistical significance was seen in Baseline ACT (s), Baseline HDR (U/mL), Baseline Slope (U/mL/s), Post Heparin Load ACT (s), first CPB AT-III (%), and Protamine (mg/Kg) (p < .05). No statistical significance was seen in the Study Intragroup between pre versus post AT-III patient load baseline sample in ACT (s), however significance was seen in HDR (U/mL) and Slope (U/mL/s) (p < .05).

CONCLUSION

Implementation of AT-III monitoring and therapy before and during CPB in conjunction with the HMS allows patients to maintain a steady state of anticoagulation with overall less need for excessive heparin replacement and potentially thrombin activation. The result is obtaining a steady state of anticoagulation, a reduced fluctuation in the heparin and ACT levels and a potential for lower co-morbidities associated with prolonged CPB times.

Blood and Blood Product Conservation: Results of Strategies to Improve Clinical Outcomes in Open Heart Surgery Patients at a Tertiary Hospital Are Maintained 4 Years after Initiation

Blood product usage is an important outcome for patients undergoing cardiac surgery. In 2015, our center made a concerted effort with multiple departments to focus on reducing transfusion rates in surgical patients requiring cardiopulmonary bypass (CPB). Specific changes included an upgrade of the oxygenator in mid-2015 and, in early 2016, implementation of a hemostasis management system (HMS) that used heparin dose-response titration assays for heparin and protamine management. A retrospective chart review demonstrated significant decreases in the quarterly average of patients receiving packed red blood cells (PRBCs) from a baseline of 26.7% to 22.7% following the oxygenator upgrade (p = .021) and from 22.7% to 8.8% following implementation of the HMS (p = .0017). Platelet usage decreased from an average of 50.5% during the baseline and oxygenator upgrade periods to 22.2% following implementation of the HMS (p < .0001). Usage of fresh frozen plasma (FFP) decreased from an average of 28.2% of cases during the baseline and oxygenator upgrade periods to 10.4% during 2016, and cryoprecipitate usage decreased from 38.5% to 15.4%. Heparin usage averaged 56,903 units before implementation of the HMS, decreasing to an average of 43,796 units following HMS implementation (p < .0001). During the same time periods, protamine usage averaged 340.3 mg and 183.2 mg, respectively. Because improvements achieved during quality initiatives may revert back to their pre-intervention state once the assessment period is over, we performed a second retrospective analysis to determine whether the improvements achieved were maintained during the 48 months following the initial study. During 2017-2020, quarterly average usage of blood products was as follows: PRBCs, 11.9%; platelets, 14.7%; FFP, 6.2%; and cryoprecipitate, 11.5%. Quarterly, average use of heparin and protamine were 31,556 ± 2,757 units and 189 ± 113 mg, respectively. These findings indicate that the improvements achieved were not limited to the duration of the initial quality initiative.